At the present time, owing in part to its predictable success, the endosseous dental implant fixture in cylindrical form is the artificial root most frequently chosen for restoring dentition to edentulous patients when implant treatment is selected. These and other forms of artificial tooth roots are conveniently designed to receive and retain, sometimes removably, a variety of intermediate components including abutments which prosthodontists use to support artificial dentition on artificial roots. The intermediate components are necessarily small parts which must be manipulated into sometimes deep posterior locations in the patient's mouth and there assembled on an existing implant fixture or fixtures into rigid and reliable structures which can withstand the forces of mastication. More and more commonly the implant fixtures have internally threaded bores for receiving small screws which are used to attach the intermediate components to the implant fixtures, and to each other, and they have hexagonal or other non-circular means for anti- rotationally engaging such intermediate components. For biological reasons the implant fixtures and intermediate components are most often made of titanium and its dilute alloys, while the screws are made of the same metals or of gold, for example.
Typical diameters of implant fixtures are from about 3 mm to about 5 mm. Typical screw diameters are about 2 mm, or less. Typically, intermediate components have diameters in the same range as implant fixtures, and lengths short enough to be encompassed within an artificial tooth, or shorter. The problems of carrying such components to an implant fixture installed in a patient's jawbone and there affixing a component to the implant with a screw, and rotating the components to engage or mate with anti-rotational features on the implant fixture, without cross-threading the screw in the threaded bore of the implant fixture, are obvious.
Abutments and other intermediate components are made in a wide variety; some are small transmucosal components as small as one millimeter long, while some are several millimeters long intended to form the core of an artificial tooth; others may extend on an axis different from the longitudinal axis of the implant fixture, for adjusting the alignment of an artificial tooth relative to its neighbors; all must be affixed to the implant fixture. To do this the dental professional must hold the component in place on the implant fixture while inserting a screw through a small hole in the component and turning the screw in the threaded bore of the implant fixture until the screw is tight and the component is firmly affixed to it. This task becomes particularly onerous when the implant fixture is installed in a posterior region in the patient's mouth.
A dental clamp for gripping a cylindrical abutment is shown in U.S. Pat. No. 5,120,221 dated Jun. 9, 1992.